Cement-burning apparatus.



L. P. BASSET.

CEMENT BURNING APPARATUS.

APPLICATION FILED JUNE 19, ms.

9 1 M ,1; Patented July 10, 1917.

I CEMENT-BURNING APPARATUS.

Specification of Letters Patent.

Patented July lo, 19117.

Original application filed July 7, 1913, Serial No. 777,735. Divided and this application filed June 19, 1915.

Serial No. 35,135.

prises two steps: the decomposition of car- I bonate of lime and the combination of liberated lime with the elementsof clay; al-.

though this latter operation requires a very high temperature, say about 1400 to 1500 Celsius, this temperature may be easily produced, as 'to this end it is only necessary to admit the required quantity of a1 r for producing the combustion of the heatlng coal.

If sulfate of lime is employed instead of carbonate of lime, it is not possible to oper-.

ate under the same conditions" and in the same furnaces, as for decomposing plaster, it is necessary to mix the latter with a quantity of coal up to about 10%. The effect of this quantity of coal is to partly convert sulfate of lime to calcium sulfid, a reducing agent, with production of carbid monoxid.

Now it is important that the atmosphere within the furnacecontain a quantity of free oxygen which is sufficient to burn the carbon oxid, as otherwise the latter would reduce the sulfur dioxid formed in the course of the reaction to sulfur and the latter would combine partly with the excess of carbon oxid, thus producing oxysulfid of carbon. Thus at the outlet of the furnace there would be a mixture of the following gases: carbonic acid, carbon oxid, nitrogen, sulfur dioxid and oxysulfid of carbon, which mixture would be of no use.

Therefore it is necessary for the purpose of recovering sulfur dioxid in the manufacture of cement by means of sulfate of lime to have within the furnace a highly oxidizing atmosphere, inasmuch as the subsequent transformation of sulfur dioxidto sulfur c acid requires a further excess of oxygen.

- The additional quantity of air which is necessary for these reactions, is about 60% I of the quantity required by the combustio of the heating coal of the furnace.

It will be easily seen that if this quantity of air be admitted in the usual Way into the furnace, the temperature of the latter would be. considerably loweredand it would be impossible to obtain the temperature required for the reaction.

This present invention has for its object to. provide an improved method complying with the requirements of temperature for the production of cement, at the same time producing sulfur dioxid freefrom carbon.

oxid and therefore directly serviceable.

This process is mainly characterized by the provision in a furnace for the manufacture of cement, of one or more additional air intakes, for the admission of air intended to burn the oxysulfid of carbon and carbon oxid produced by the decomposition of sulfate of lime, this or these additional airintakes being provided either at the end of the furnace or in an auxiliary chamber connected to said furnace-end so that the temperature of the furnace is not lowered by the admission of additional air. Y

J Furthermore by adjusting the additional air admission it is possible to produce variations in the com osition of the gases produced by the ecomposition of plaster, without modifying the operation of the furnace. p In order to facilitate comprehension, I have illustrated diagrammatically in the accompanying drawings the application of my invention to a rotary furnace used for the manufacture of cement.

Figure l is a vertical longitudinal section of one form of apparatus for practising my process.

Fi 2 is a preferred form.

Re erring to Fig. 1 of these drawings, the furnace a has at one end a nozzle 6 through which the heating coal and combustion air are injected, the quantity of air being just suflicient to burn the coal and produce a weakly oxidizing flame. Therefore in the hearth of the furnace I produce the high est temperature of the combustion which is necessary for combining lime with the elesure. In this case the nozzle 0 may ranged to discharge into the furnace from a chamber (1, into which air is forced by ineans of a ventilator.

Air may also be blown into the furnace by means of an electric ventilator secured to the furnace and rotating with the same; the electric current is supplied to the motor of this ventilator through the agency of rings arranged concentrically to the furnace and with ,which brushes are frictionallyengaged.

Air may also be introduced through a central pipe 6, bent at its end as shownin Fig. 2, so that the air injected through this pipe will not counteract the draft of the furnace.

Air may also be admitted by suction.

The furnace may be equipped with a plurality of additional air-intakes, arranged over a certain. portion of its length, so as to produce an. oxidizing atmosphere throughout the length of the furnace.

Through the end of the furnace opposite to the hearth I introduce the mixture of sulfate of lime and clay, to which is added coal.

This mixture travels through the furnace in a direction opposite to that of the combustion gases; at the discharge end of the furnace this mixture is first dried; afterward in the part .of the furnace where the temperature is raised to about 900 C. the mixture will be decomposed to lime, carbon oxid and sulfur dioxid, and finally lime will be combined with clay in the hearth where the temperature is raised to 1500 C. to produce cement.

The carbon oxid and sulfur dioxid which are set free by the decomposition of sulfate of lime, are not compatible and produce oxysulfid of carbon.

However this oxysulfid of carbon as well I as the excess of carbon oxid and sulfur dioxid meeting with the additional air introduced through the nozzle or nozzles 0, will be burned, thereby raising the temperature, and at the discharge of the furnace there will only escape together with the gases of combustion sulfur dioxid entirely free from carbon oxid and an excess of air. in determinate quantities so that the sulfur dioxid may be converted to sulfuric acid in a lead chamber or any other suitable apparatus arranged in series with the furnace.

e ar-' The combustion of oxysulfid of carbon and carbon oxid formed within the furnace may also be produced in an auxiliary combustion chamber, connected to the discharge end of the furnace and into which I admit the necessary quantity of air for burning said oxysulfid of carbon and carbon oxid; said combustion air may be introduced in a cold state or previously heated.

As the gases are discharged from the furnace at a rather high temperature and as the combustion of carbon oxid contained therein produces also a considerable quantity of heat, it will only be necessary to ignite these gases once within said auxiliary combustion chamber.

As already mentioned above this present invention provides means for producing sulfurous gases which may be used directly and also means for controlling the composition of the gases produced within the furnace, independently from those of the hearth. Thus for example if the temperature of the furnace is temporarily lowered, the reaction of decomposition will be necessarily retarded, however the composition of the gases may be maintained constant by reason of the possibility of varying the quantity of air introduced into the furnace through the additional air-intakes.

I wish it to be understood that a rotary furnace has been described merely by way of example .and that the invention maybe used in connection with any other furnace.

I claim:

In a cement burning apparatus, the com bination of a furnace having a length many times greater than its width, an injector for air and fuel at the material-outlet end, a pipe extending into the furnace at the gasoutlet end, said pipe being bentupon itself to deliver in the direction of the draft through the furnace, and opposite to the direction of the travel of the solid material therethrough, and at a point at which the normal temperature is about 9009 C. and means for regulating the blast delivered by said pipe.

In testimony whereof I have hereunto set my hand in presence of two witnesses.

LUCIEN PAUL BASSET.

Witnesses:

JOHN BAKER, HANSON C. Coxn. 

